Socket Cap Screws

Knurled Head Cap Screws with an Internal Hex Allen Drive

A socket cap screw is a fastener driven with a socket wrench with a knurled head. A socket cap screw is a type of cap screw with a cylindrical head and hexagonal drive hole. The term socket head cap screw typically refers to a type of threaded fastener whose head diameter is nominally 1.5 times or more that of the screw shank (major) diameter.